using the deleted keys from an access db with autoincrement

That is a very, very bad idea - you can do it, but it can cause all sorts of problems. For example, what if you get a new record request from two different users at the same time? They could both decide to use an id of "3" with the identification problems that that will cause.
If you really want a sequential number for records, then don't use the record ID - keep that as a separate object - and use the ordinal number instead.